Another Td5 Discovery mpg question

Hi, Have had my Disco about 6 months now. Its a 2000 reg auto.
When i first had it i worked out i was doing around 23mpg around town. I noticed i was losing diesel and so had the fuel pressure regulator done and removed the egr valve and worked out i was doing about 25mpg.

Then the head gasket went (Stupid plastic dowels). So had that done by my local specialist and since then i appear to be getting 19.7mpg.

I know its colder at the moment and i know Td5's especially autos are pretty rubbish on fuel economy but this is just ridiculous. And i turn the climate control to Econ every time i get in.

What could the garage possibly have done thats caused this sudden loss in mpg? Or what else could it be?

Im seriously thinking of getting rid of it and getting an older tdi.

Any help would be much appreciated.

Thanks

Great. Last 200 miles, 70 quid worth of diesel, 54 litres, 17mpg. It just keeps getting better.

What can I do?

I`d visit that local specialist and talk to him!
Your mpg really is out of range.

Take it back to the garage who did the work and get them to fix it - why would you do anything else? You did pay them to fix a problem didn't you?

Good luck

Dave

Yes i did and they did fix the head gasket. Im just trying to figure out what they could have possibly done. No harm in that is there? going back in next week.

Thanks

Oil level not risen, I'm guessing. Not by enough to get those figures anyway!

TD5mm said:

Yes i did and they did fix the head gasket. I'm just trying to figure out what they could have possibly done. No harm in that is there? going back in next week.

Thanks

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None whatsoever, but as I said before if you pay someone to solve your problem and they don't - they should put it right.

Without further info and diagnostic results any other advice would just guesswork. Your fuel consumption has reduced by 25% but how do you know if your driving style is identical, if the fuel quality was the same, the journeys the same etc etc etc.

You haven't really given us a lot to work on, so a proper full diagnosis is what is required before any problem can be identified.

thebiglad said:

None whatsoever, but as I said before if you pay someone to solve your problem and they don't - they should put it right.

Without further info and diagnostic results any other advice would just guesswork. Your fuel consumption has reduced by 25% but how do you know if your driving style is identical, if the fuel quality was the same, the journeys the same etc etc etc.

You haven't really given us a lot to work on, so a proper full diagnosis is what is required before any problem can be identified.

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I`d say he could come to my shop on saturday but with that MPG that would cost him a fortune

Thanks guys. Taking it in next week now so hopefully they will find the problem. Was thinking they may have got the fuel pump timing out a tooth or injector proramming. Hopefully something like this will show up on a diagnostic computer.

Will let you know how i get on.

Ok been on computer today and cane up with 2 faults. Maf sensor fault and number 3 injector wiring open circuit fault. Is this just a replacement of the injector loom that I keep reading so much about? How easy is it to do? Also would the Maf fault come up if I just disconnected the sensor to clean the sensor? I did this a while back way before I had any fuel consumption problems. The ignition was off though. Just seems like it is a good contributor to such poor mpg. Well I hope so anyway. Lol.

Thanks

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Drive for a while and then test again, if the faults are there again change the parts.

Ok sounds a good idea. But surely its not just coincidental that my fuel consumption has decreased so much and these two faults are logged on the system.

Anyone know how big a job it is to do the injector harness? Am I right in saying that if number 3 injector is not working due to being open circuit that the fuel would just be burnt off through the exhaust system instead causing poor mpg?
Also if the Maf is faulty then could be telling ecu to put more fuel in again causing poor mpg?

Thanks again

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Had a look at the injector harness today and removed te plug from the ecu to find it full of oil so i am going to change the harness anyway.

Then il drive it round for a week to see if any improvement and then get it back on the computer to check for the faults.

Thanks

Hi again. Well i changed the injector wiring harness on its own. Removed the ecu and found a hell of a lot of oil inside the plug connecting to the ecu. See picture attached!

I cleaned everything down and fitted the new harness. I ran it around for a week with no obvious effect to my mpg.

Took it back to be put on the computer today and both faults on there again. Although i did drive the truck for a couple of days before i changed the harness so the faults could have happened in that space of time. I believe the Maf sensor and the injector harness both go back to the same red plug on the ecu (please correct me if im wrong?) So possibly oil shorting out pins in plug - maybe??? Anyway the guy reset the faults and i went a drive for 15 minutes and then went back and now no faults whatsoever. Could it be that, that short space of time was not long enough to bring up the maf sensor fault? Or if the sensor is faulty would it fault out straight away?

If there is a fault logged would this prevent that piece of equipment working? Like if the abs light is on it is said that the abs will not work. Would this be the same with the maf sensor/injectors? as the faults were still there after i changed the harness. The maf fault is Air flow high fault.

Anyway i have worked out i am doing roughly 19.5mpg around town. Not been on a long enough run yet. So looks like a slight improvement if any.

I know the car could do with a service but would this improve the mpg by so much to get it back to around 24mpg around town?

Is a K&N air filter really worth the money when servicing it?

Now the harness has been changed and the faults reset i plan on running it for another week and then get it back on computer to see if they have popped back up again.

Sorry to rant on about it. Thanks for everyones help and comments. I really appreciate it.

if the car needs a service then service it, it can have an effect on mpg